Smoking Increases Heart Defects In New Borns

March 4, 2011

Babies being born with some very common types of birth defects have been attributed to mothers who smoke during their first trimester of pregnancy, according to a new study.

The findings show that women who smoked early in pregnancy were 30 percent more likely to give birth to babies with obstructions in the flow of blood from the heart to the lungs, and nearly 40 percent more likely to have babies with openings in the upper chambers of their hearts.

“For women who are planning to become pregnant, if they are smokers, they should stop smoking,” study author Dr. Adolfo Correa of the Centers for Disease Control and Prevention (CDC) told Reuters Health. And if they find out they are indeed pregnant, “they should stop smoking” immediately.

Correa and colleagues reviewed data of mothers of 2,525 infants with congenital heart defects and mothers of 3,435 similar infants who were born with health hearts. They focused on two types of heart defects already linked to smoking in pregnancy — obstructions in blood flow from the right side of the heart to the lungs and openings between the upper chambers of the heart.

The openings in the heart’s upper chambers occur in about one in 1,000 babies, and obstructions in blood flow occur at a rate of about 1 in 1,800 babies in the US, Correa noted.

Based on their findings, if mothers choose to smoke during pregnancy, those rates increase — women who smoked during early pregnancy were 36 percent more likely to have a baby with these abnormal openings, and 32 percent more likely to have a baby with obstruction in blood flow to the lungs.

Correa said that smoking in the second and third trimesters may also pose threats to the unborn child, but he and his colleagues focused only on the first trimester because this is the time when most organs are being developed, and the fetus is more susceptible to “the effects of environmental conditions.”

Most women, however, are less likely to know they are pregnant in the first trimester, said the team, making it even more imperative they stop smoking before any chance of pregnancy occurs.

Correa noted that it remains unclear how smoking may affect heart development. He thinks that it might somehow lower levels of folate, known to prevent birth defects. “We don’t really know the mechanism for how smoking might be associated with heart defects,” said Correa.

The Centers for Disease Control and Prevention says that 40,000 babies are born every year with some type of congenital heart defect. And a news release form the CDC adds that the study suggest that if women quit smoking before or early on in pregnancy, they could avoid as many as 800 cases of heart-related birth defects every year in the United States.